
package org.apache.solr.search;

import java.io.IOException;

/**
 * Implementations of <code>CacheRegenerator</code> are used in autowarming to populate a new cache
 * based on an old cache.  <code>regenerateItem</code> is called for each item that should be inserted into the new cache.
 * <p>
 * Implementations should have a noarg constructor and be thread safe (a single instance will be
 * used for all cache autowarmings).
 *
 *
 */
public interface CacheRegenerator {

    /**
     * Regenerate an old cache item and insert it into
     * <code>newCache</code>
     *
     * @param newSearcher the new searcher who's caches are being autowarmed
     * @param newCache where regenerated cache items should be stored. the
     * target of the autowarming
     * @param oldCache the old cache being used as a source for autowarming
     * @param oldKey the key of the old cache item to regenerate in the new
     * cache
     * @param oldVal the old value of the cache item
     * @return true to continue with autowarming, false to stop
     */
    public boolean regenerateItem(SolrIndexSearcher newSearcher, SolrCache newCache, SolrCache oldCache, Object oldKey, Object oldVal) throws IOException;
}
